CaV3.2 Channels and BKCa-Mediated Feedback in Vascular Smooth Muscle

The vascular T-type Ca2+ channel, CaV3.2, regulates arterial tone by triggering Ca2+ sparks and activating large conductance Ca2+-activated K+ (BKCa) channels. Despite being an integral element of an arterial feedback loop, little is known of its regulation and how key receptors and signaling pathways use this channel to influence tissue perfusion. This thesis will begin to fill key knowledge gaps, undertaking experiments that progress from individual smooth muscle cells to whole arteries, and which entail the use of patch clamp electrophysiology, Ca2+ imaging, pressure myography, immunohistochemistry, quantitative polymerase chain reaction (qPCR) and computational modeling. In initial work, perforated patch electrophysiology was used in concert with Ca2+ imaging to illustrate the coordinated interplay between CaV3.2 and two other Ca2+ permeable conductances in setting voltage-dependent Ca2+ spark production and BKCa channel activation. A second layer of experiments subsequently revealed that caveolae help couple CaV3.2 to Ca2+ sparks generation by placing this T-type Ca2+ channel in close proximity to its intracellular target, ryanodine receptors (RyR). Disruption of the structural arrangement impaired the ability of CaV3.2 to mediate BKCa-mediated feedback in intact resistance arteries. Final experiments revealed that CaV3.2 channels are targeted by common vasoactive stimuli through unique signaling pathways. Of note, was the ability of Angiotensin II to suppress CaV3.2 channel activity through the generation of reactive oxygen species (ROS) by NADPH oxidase (Nox). In summary, this thesis advances our knowledge of Ca2+ handling in vascular smooth muscle by providing new regulatory insight into CaV3.2, a T-type Ca2+ channel involved in optimizing arterial tone and tissue perfusion.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Cardiovascular & Respiratory Sciences

Grantor dc:publisher.institution

Cumming School of Medicine

Year dc:date.issued

2018

Author dc:creator

• Hashad, Ahmed Mohamed

Advisors dc:contributor.advisor

• Welsh, Donald Gordon
• Chen, Sui Rong

Committee members dc:contributor.committeemember

• Altier, Christophe
• von der Weid, Pierre-Yves

• Calcium Channels
• Vascular
• Arterial Tone
• Calcium Sparks
• Cerebral

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/32277

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/107055